The present invention relates to heat exchangers. More particularly, the invention relates to heat exchangers for cooling compressed air produced by multi-stage air compressors.
Typical gas compressors include a heat exchanger for reducing the temperature of the compressed gas. The heat exchanger or cooler reduces the temperature of the compressed gas or air to a predetermined temperature to make the compressed air easier to use. Shell and tube type heat exchangers are commonly employed in air compressors. Typically, the shell side of the heat exchanger carries the cooling fluid, normally water. In these conventional coolers the tubes typically contain the compressed air. The water flows through the cooler shell over the cooling tubes and the connected heat transfer fins as the air passes through the tubes. This conventional arrangement facilitates the transfer of heat from the compressed air to the water.
These conventional shell and tube type heat exchangers have several disadvantages. For example, the heat exchangers are difficult to maintain. The flow of water over the tubes generally results in the production of fouling and corrosion products on the shell side of the heat exchanger. The complicated geometry associated with the heat transfer fins and other components extending through the shell side make the fouling difficult to remove. Furthermore, existing heat exchanger designs can not accommodate multi-stage air compressors. Current heat exchanger designs require a separate heat exchanger or cooler for each compressor stage. Each heat exchanger requires its own water supply and must be maintained and serviced separately. Accordingly, there is a need for a single heat exchanger with improved serviceability that may be used to cool compressed air from multiple stages of a multi-stage air compressor.
The present invention addresses these needs.
According to one aspect of the present invention a heat exchanger comprising a plurality of cooling chambers configured to receive heated fluid is provided. Each cooling chamber includes a heated fluid inlet and a heated fluid outlet. The heat exchanger includes a cooling tube adapted to carry cooling fluid and positioned to pass through each of the plurality of cooling chambers. The cooling chambers may be operatively connected in series so that heated fluid leaving the outlet of a first cooling chamber enters the inlet of a second cooling chamber. In a preferred alternative, the cooling tube is positioned to carry cooling fluid sequentially through each of the cooling chambers.
The heat exchanger may further comprise a second cooling tube positioned to pass through each of the cooling chambers and adapted to carry cooling fluid sequentially through each of the cooling chambers so that the cooling fluid in the second cooling tube passes through the cooling chambers in the opposite direction to the cooling fluid in the first mentioned cooling tube. The first and second cooling tubes may be operatively connected in series.
Each cooling tube may include a plurality of heat transfer fins connected to the cooling tube and positioned to extend into each of the cooling chambers. Preferably, the cooling tube is cylindrically shaped and each of the fins extend radially outward from the tube. Preferably, the fins are configured in a herringbone or wavy configuration.
The heat exchanger may include a housing enclosing the cooling chambers and the cooling tube and a dividing wall positioned to separate the cooling chambers. The dividing wall may include an opening for receiving the cooling tube. The heat exchanger may further include a sealing mechanism positioned between the housing and an edge of the dividing wall to prevent mixing between the heated fluid contained in the cooling chambers. The housing may include a pair of manifolds positioned at opposite ends of the cooling chambers, wherein the first manifold is connected to a first end of the cooling tube and the second manifold is connected to a second end of the cooling tube.
According to another aspect of the present invention a multi-stage air compressor is provided. The air compressor includes a heat exchanger for cooling compressed air comprising a plurality of cooling chambers configured to receive compressed air; and a cooling tube configured to carry cooling fluid through each of the cooling chambers. The heat exchanger may be configured so that the compressed air exiting a first compressor stage passes through the first cooling chamber and into a second compressor stage; and the compressed air exiting the second compressor stage passes through the second cooling chamber.
The heat exchanger may include a second cooling tube configured to carry cooling fluid through each of the cooling chambers in a direction opposite to the first mentioned cooling tube, wherein the first and second cooling tubes are operatively connected in series so that cooling fluid exiting the first cooling tube enters the second cooling tube. The heat exchanger may also include a plurality of heat transfer fins connected to the cooling tubes and positioned to extend into each of the cooling chambers. The cooling tubes may be generally cylindrically shaped and each of the fins may extend radially outward from the tube.
The heat exchanger may include a housing enclosing the cooling chambers and the cooling tube. The housing may includes a pair of manifolds positioned at opposite ends of the cooling chambers, wherein the first manifold is connected to a first end of the cooling tube and the second manifold is connected to a second end of the cooling tube. The housing may include a dividing wall positioned to separate the cooling chambers. The dividing wall may include an opening for receiving the cooling tube. The heat exchanger may further comprises a sealing mechanism positioned between the housing and an edge of the wall to prevent mixing between the compressed air contained in the cooling chambers.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.